基于开挖弃土和粉煤灰制备泡沫轻质土（foamedlightweight soil using excavated soil and fly ash，简称FLS-FE），并将其用于软土地区路基填筑或路基强弱交界处不均匀沉降控制是一种绿色环保且行之有效的处治方案。基于这一理念，通过一系列室内试验研究了不同比例下泡沫轻质土的流动度、吸水率、无侧限抗压强度变化规律，并进一步开展了干湿循环与冻融循环试验，揭示了FLS-FE长期服役状态的演化规律。试验结果表明，FLS-FE的流动度受开挖弃土和粉煤灰的影响较大，粉煤灰和熟石灰可以降低其吸水率。干密度与抗压强度变化一致；随开挖弃土掺量提高，FLS-FE抗压强度显著降低；然而粉煤灰与熟石灰的掺入均能有效提升其强度与韧性，尤其通过添加4%熟石灰进行碱激发以活化固废分子活性，可使抗压强度提升43.9%。在耐久性方面，单独加入开挖弃土且掺量≤50%时，20次循环后强度损失不超过30%，掺量为60%时FLS-FE强度损失在干湿循环下达到46%，冻融循环下达到40%，添加粉煤灰可显著缓解强度衰减。通过添加熟石灰提供碱性环境后，FLS-FE经过20次干湿循环质量损失低于13%，冻融循环下低于12%；耐久系数均大于70%。基于试验研究成果，建议用于路基填筑的FLS-FE中开挖弃土含量不宜超过50%；通过添加粉煤灰，可使得总体固废利用率达60%，添加4%含量的熟石灰能够最大程度提高FLS-FE的性能。The utilization of excavated soiland fly ash to produce foamed lightweight soil (FLS-FE)

and its application insubgrade filling in soft soil areas or the control of uneven settlement at thetransition zones between strong and weak subgrades

are a green

environmentally friendly

and effective treatment solution.Guided by concept

a series of laboratory tests were conducted to investigatethe variation patterns in fluidity

water absorption

and unconfinedcompressive strength of FLS-FE at different mixing ratios. Further wet-drycycling and freeze-thaw cycling experiments were implemented to reveal theevolution patterns of FLS-FE under long-term service conditions. The testresults indicate that the fluidity of FLS-FE is significantly influenced by thecontent of excavated soil and fly ash

while fly ash and hydrated lime can reduce its water absorption. The dry density correlates withcompressive strength changes. As the excavated soil content increases

thecompressive strength of FLS-FE decreases significantly. However

theincorporation of both fly ash and hydrated lime can effectively enhance itsstrength and toughness. In particular

adding 4% hydrated lime for alkaliactivation to stimulate the reactivity of the solid waste molecules canincrease the compressive strength by 43.9%.In terms of durability

whenincorporating excavated soil alone at ≤50% dosage

the strength lossafter 20 cycles does not exceed 30%. At a 60% dosage

the strength loss ofFLS-FE reaches 46% under wet-dry cycling and 40% under freeze-thaw cycling.However

The addition of fly ash can notably mitigate this strengthdegradation. After introducing hydrated lime to create an alkaline environment

the mass loss of FLS-FE remains below 13% after wet-dry cycles and below 12%after freeze-thaw cycles

with durability coefficients consistently exceeding70%. Based on the experimental findings

it is recommended that the content of excavatedsoil in FLS-FE for subgrade filling should not exceed 50%; the overall solidwaste utilization rate can reach 60% by incorporating fly ash

and adding 4% hydratedlime can maximize the performance enhancement of FLS-FE.